Hydraulic tappet



Dec. 23, 1941. R w osBoRN t `HYDRAULIC TAPPET Filed March 6, 1941 MPR Oson Patented Dec. 23, 1941 yHYDRAULIC TAPPET Ralph W. Osborn, Muskegon Heights, Mich., as-

signor to Johnson Products, Inc., `Muskegon Heights,rMich., a corporation of Michigan Application Marche, 1941, serial No. 382,052

i Claims. (cl. 12s-9a) This invention relates to hydraulic tappets and is concerned with improvements in connec- I tion therewith whereb-y economy in manufacture of parts and in their assembly is greatly facilitated, resulting in an ability to manufac- I `ture the tappets and sell them at a price which can beaiiorded by the purchaser of large quan- `titiesthereof for use in internal combustion en-` gines, and with a proiit to the manufacturer.

A furtherobject of the invention is to provide a tappet construction which is particularly practical `and eiiicient in use, which will not get out "of order and which has no parts liable to need replacement or repair. At the same time if replacement of parts is needed or if the tappet c needs to `be disassembled for cleaning or other Where such groove is made, providing a continuous annular rib or ledge 4 as shown surrounding` a central opening 5. A plurality of horizontal holes 6 connect the groove 3 with the opening 5. The opening 5 ext-ends upwardly part way through the rib or ledge 4 at the upper part of which there is a larger shallow opening 1 yei;- tending from the upper end of the opening `5 vto the upper side of said rib or ledge 4.

A sleeve member which may be drawn and pressed `from flat stock consists of a lower cylin- -drical relatively long sleeve portion 8, an out'- Wardly` extending continuous horizontal rib 9 and an upper short sleeve section I0, the diam.-

eter of which preferably is less than that of the v lower section 8. The rib 9 is provided by extendservicefthe construction lends itself in a particuvlarly` eiective way to serve such purpose.

`An understanding of the invention may be had from the following description, taken in conneci tion withV the accompanying drawing, in which- Fig. l is a longitudinal vertical section through a hydraulic valve tappet constructed in accordance with my invention.

Figs. 2 and 3` are similar sections through the ftwo parts of the movablepiston member of the tappet as they are manufactured and previous to `their i connection.

Fig. 4 is a similar central vertical section after ythe` two parts shown in Figs. 2 and 3 have been `the sleeve member which extends into the oil reservoir of the tappet and makes a communication between said oil reservoir and the under side of the piston, the upper end of said sleeve being normally closed by the hat` plate valve shown in Fig. 5. I

Like reference characters refer to like parts in the diiierent iigures of the drawing.

vThe body I ofthe valve tappet is of a cylindri-` cal form and is substantially hollow, open at its upper end and integrally closed at its lower end by the bottom 2, the under side of which is designed to bear against a cam of the cam shaft of an internal combustion engine. Intermediate the upper and lower ends of the body and continuous around the same is an annular groove 3. The body is thickened inwardly at the place ing the tubular sides of the member outwardly as shown in Fig. 8 so that the rib consists substantially of two thicknesses of the metal integrally connected at their outer edges, the two lthicknesses of metal lying against each other. The outer edge of the rib S is of a diameter such that it may be forced into the upper shallow opening 'l in the rib 4 previously described,` the conn-ection being a tight one or a press fit. This closes off in the lower part of the body I `an oil reservoir or chamber II into which the lower sleeve portion 8 extends, nearly to its bottom as shown in Fig. 1. The oil reservoir II is connected through the opening 5 and the passages E with the groove 3.

A flat metal valve I2 of circular outlineznormally rests upon the upper end of the upper sleeve section I0 being pressed thereagainst by a light coiled spring I3 which with the valve is housed and retained in a sheet metal cage. The cage has an upper extension I4 of a diameter sucient to receive the upper end of the spring I3, and a lower larger cylindrical portion I5` at the lower edges of which a horizontal flange I6 is turned outwardly. From the flange a plural` ity of fingers Il, shown as three in number, are struck and turned inwardly to lie underneath the plate valve I2. When the cage with the valve and spring therein is assembled in the structure it is placed over the upper part IIJ of the sheet metal sleeve, the inner ends of the fingers I'I guiding the cage into place by reason of their close proximity to the outer sides of the part I0. The ange I6 extending outwardly goes beyond the limits of the opening 1 and lies upon the upper side of the rib or ledge 4 (see Fig. 1).

In the upper open portion of the body I- a piston of a special construction is mounted.

In producing this piston a lower part of inverted cup shape form is pressed from at metal having a top I8 and cylindrical sides I9. The outer edge portions of the top I8 are curved outwardly and downwardly and meet a narrow annular ledge 20 as shown in Fig. 3. The outer diameter of the member at such ledge 20 isv slightly less than the outer diameter of the depending sides I9 and is continued downwardly for a short distance until a second narrow annular ledge 2| is reached, said ledge 2I forming a junction with the outer sides of the depending sides I9 of said cup member. At this position between the ledges 2] and 2| horizontal openings 22 are made through the member as shown. The upper member of the piston is also pressed from :dat metal having a top 23, preferably of the form shown, with depending sides 24 which at their inner portions and at their under edges are shaped with a curved annular recess 24a. as shown, to lit the downwardly and outwardly curved sides of the top I 8 where it joins with the 4depending sides of the first member.

The two members are placed together as shown in Fig. 4 fitting closely at their contacting points and are securely welded to make in eifect an integral structure. The outer diameter of the depending sides 24 is the same as that of the depending sides I9 thereby providing in the completed structure a continuous shallow groove 25 with which the passages 22 connect.

' 'The interior of the upper portion of the body I is properly machined to a prescribed size and the exterior diameter of the piston is likewise 'machined so as to t therein with a reasonably close t but not be tight or binding so thatthe piston member may have free vertical movements within the tappet body. A coiled compression spring 26 surrounds the valve holding cage previously described, bearing at its lower end upon the flange I6 and at its upper end yagainst the under side of the part I8 which forms a horizontal partition through the assembled piston. The usual retaining snap ring 2'I of spring wire material is seated in the groove at the inner side of and at the upper end of the body. The valve stem 2S, of the internal combustion engine of which this tappet is a part, holds the piston in an intermediate position between the snap ring 2l and the bottom of the upper chamber of the body of the tappet.

The valve tappet described is used in an engine in the usual manner of hydraulic tappets mounted for reciprocation in a guide and with a communication for the passage of oil under the pressure of the oil pump of the engine to supply' oil continuously to the groove 3 which will be closed at its outer portions by the guide for the tappet, therefore the reservoir at II is supplied with oil which enters at the lower end of the sleeve portion Ill by going past the valve and passing through the openings in the side and top of the sheet metal cage, said cage being vented with openings for such purpose. This provides oil to ll the hydraulic chamber underneath the part I8. The openings at 22 will permit escape of air contained in the tappet before the oil was let into the tappet, into the groove `25 and thence upwardly between the walls of the piston and the inner walls of the tappet body. After this initial air is once expelled from the hydraulic chamber it very seldom happens that any more air ever gets into it, but if it does, it is expelled in the same way. Itis not neces- Vsary to describe the operation of the tappet in detail as such tappets in general are known in the art.

The construction lends itself particularly to simplicity of manufacture and assembly with a resultant economy. The parts of the tappet which need to be machined are the outer curved sides and the under at side of the body, the inner sides of the upper portion of the body, the outer sides of the piston, the edges of the rib 9 and the sides of the shallow recess at I. And by machining is meant a making to accurate size which so far as the sheet metal parts are concerned is accomplished by dies. The assembly is merely forcing the sleeve member 8, 9, Il] into place, putting the valve cage over the projecting upper end I0, then putting the spring 26 in position, inserting the piston and nally the retaining spring ring 21. The construction is particularly simple. It is effective in practical use.

k'I'he construction of tappet described is very practical from a manufacturing standpoint. On

forcing the sleeve member 8, 9, IU into place, the

middle portion of the body I is slightly enlarged eXteriorly, and the bottom portion of the open upper half of the body is likewise enlarged. But with this construction the outer cylindrical surface of the body is ground to remove any slight intermediate enlargement while the interior of the upper portion of the body is bored to make the inner walls vertical and not tapered at any portion, the assembly of the valve unit, the spring 26 and the piston being done after the final machining operation of interiorly boring the upper end portion of the body I.

A further feature of advantage of the tappet resides in the shallow recess or reservoir at 'I above the rib 9 on the central sleeve member. Any dirt or other foreign material which might get in the oil and, if it should become interposed between the upper end of the part I0 and the lower side of the valve I2 would interfere with the operation, settles into such shallow recess I and stays there indefinitely, not being stirred up or aifected in any manner.

The piston construction illustrated in Figs. 2, 3 and 4 is of particular utility. It can be manufactured from flat metal by dies, greatly reducing the expense of production over pistons which might serve the same purpose made from solid bar stock. After the parts are welded together, all surfaces except those housed within the upper member 23` are hardened and the outer cylindrical surfaces ground to accurate size. The piston is light but is very strong by reason of its constructive design.

The invention is dened in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. In a hydraulic tappet, a hollow cylindrical body open at one end and closed at the other and having an inwardly extending annular ledge at its inner side, there being an opening through the ledge enlarged at its upper portion, and a sleeve member provided a short distance below its lower end with a continuous annular rib inserted downwardly through said opening in the ledge and forced with a press t at said rib into the larger upper portion of said opening, as specified.

v2. In a hydraulic tappet, a hollow cylindrical body open at one end and closed at the other andy having an inwardly extending annular ledge at its inner side, there being an opening through the upper side of the rib in a plane below the upper side of said ledge, providing a shallow annular space around the sleeve above the rib.

3. The improvement in hydraulic tappets, wherein the tappet has a hollow cylindrical body closed at one end and open at the other and has an inwardly extending ledge with a central opening therethrough disposed between the upper and lower ends of the body and within the same, and is provided with a piston hollowed out at its under side above said ledge, said improvement consisting in providing a vertical sleeve drawn from flat metal and formed a short distance below its upper end with an outwardly extending continuous annular rib connected with the ledge and transversely filling the opening through said ledge, a flat valve lying against the upper end of the sleeve, a spring bearing against said valve, a sheet metal cage open at its lower side enclosing the valve and spring into which the upper end of the sleeve member extends, said cage at its lower end bearing against the upper side of the ledge, and a coiled compression spring means between said piston and said cage, said means extending upwardly into the lower hollowed out portion of the piston.

4. In a hydraulic tappet, an oil reservoir and a hydraulic chamber therein, a vertically positioned sleeve member having a lower relatively elongated sleeve portion, an upper much shorter sleeve portion and an integral outwardly extending continuous annular rib of circular outline between the upper and lower portions of the sleeve, said rib adapted to have a pressure iit against the body of the tappet to form a liquid connection between said oil reservoir and hydraulic chamber.

5. A construction comprising the sleeve member as defined in claim 4, a flat valve adapted to lie over the upper end of the sleeve member, a coiled compression spring bearing at one end against the upper side of the valve, a sheet metal cage covering the spring and valve and surrounding the upper end portion of the sleeve member, said cage being open at its lower side and having an outwardly extending flange at its lower edges with lingers struck from said flange and turned inwardly toward each other, the ends of said fingers lying closely adjacent the outer sides of the upper end of said sleeve member thereby locating cage, valve and spring with reference to the upper portion of the sleeve member.

6. In a hydraulic tappet, a cylindrical hollow body closed at its lower end and open at its upper end and provided with a continuous inwardly extending horizontal ledge at its inner sides be tween its upper and lower ends, said ledge having a central opening therethrough which is enlarged at its upper end portion, and said body having an exterior groove between its upper and lower ends at the outer portions of said ledge with horizontal passages extending from said groove through the ledge, a tubular sleeve member inserted at its lower portion downwardly through said openingand provided with a rib having a circular outline located in the upper enlarged portion of said opening through the ledge and in tight engagement with the sides thereof, the upper side of said annular rib being below the upper side of the ledge, a piston mounted within the upper portion of the body having a recessed under side, the upper end portion of the sleeve member extending above said ledge, a plate valve covering the upper end of' the sleeve member, a spring bearing against the upper side of the valve, a sheet meal covering cage ventilated by openings therethrough housing said spring and valve and at its lower edges provided with an outwardly extending flange bearing against the upper side of the ledge, said flange having fingers struck therefrom and turned inwardly toward and positioned around the upper end of the sleeve member, and a coiled compression spring engaging at its lower end with said sheet'metal cage and at its upper end against the piston at the upper part of the recessed under portion thereof.

7. A hydraulic tappet having an oil reservoir and a hydraulic chamber therein, an opening between the oil reservoir and hydraulic charnber, a vertically positioned sleeve member extending at its lower end into the oil reservoir and at its upper end into the hydraulic chamber, and a laterally extending continuous annular rib on said sleeve member closing said opening and having a pressure lit with the body to maintain a liquid tight exclusion between said oil reservoir and hydraulic chamber except lengthwise through the interior of the sleeve.

RALPH W. OSBORN. 

